This invention relates to a vehicle air-conditioning system, and more particularly, to an vehicle air-conditioning system useable in a hybrid vehicle and a economy-run vehicle.
A vehicle air-conditioning compressor is generally driven by an engine, and in the case of a hybrid vehicle and an economy-run vehicle, the compressor will stop if the engine stops even when the air conditioning system is ON. The surface of the evaporator commonly has debris that emits offensive smells (perfume, new vehicle trim, cigarettes). Usually, these offensive smells are covered with condensate that holds them to the surface of the evaporator. As such, they do not scatter into the vehicle interior.
However, if the compressor stops operating, the condensate holding the particles to the evaporator evaporates, and therefore offensive smells leave the evaporator with the air-conditioned fresh air into the vehicle interior. According to JP-A No. Hei 11-198644, the compressor stops until offensive smells are detected, thereafter being restarted to thereby prevent offensive smells from entering the vehicle interior. Furthermore, the compressor operates until the air temperature passing the evaporator lowers to a predetermined value, and then is stopped again. However, the compressor should operate until immediately before the occurrence of an offensive smell, and also until the temperature of the air after passing through the evaporator lowers to the predetermined value. Because of this, it is difficult to decrease compressor speed.
In view of the above-described disadvantages, the present invention provides an air-conditioning system having a compressor which compresses refrigerant, and an evaporator mounted inside of an air-conditioner casing forming an air passage through which the fresh air is blown into the vehicle interior, to thereby cool the air by evaporating the refrigerant. According to this invention, the air-conditioning system has a first clock means which measures time from compressor stop, and a second clock means which measures time after compressor start, so that the compressor will start when the time measured by the first clock means after compressor stop has reached a first predetermined time. The compressor operates until the time measured by the second clock means reaches a second predetermined time which is shorter than the first predetermined time.
The flow velocity of the refrigerant at which the ratio of surface sweating (the velocity at which the surface of the evaporator dries) can be decreased by the short-time flow of the refrigerant in the evaporator, thereby keeping offensive smells covered with condensate. Furthermore, since the compressor is operated after the lapse of the first predetermined time To after the compressor has been stopped, the rate of operation of the compressor can be lowered.
In another aspect of the invention, the compressor and the evaporator are mounted inside of the air-conditioner casing forming an air passage through which the fresh air is blown into the vehicle interior, thereby cooling the air by evaporating the refrigerant. According to this invention, the air-conditioning system has a first clock means which measures time from compressor stop, and a second clock means which measures time after the start of the compressor. An intermittent operation mode is executed to perform the compressor on-off operation to stop the compressor until the compressor, after stopping, will be kept stopped until a time measured by the first clock means reaches a first predetermined time, and thereafter to operate the compressor until the time measured by the second clock means reaches a second predetermined time that is shorter than the first predetermined time.
Thus, the rate of evaporation (the rate at which the surface of the evaporator dries) is reduced by the short-time flow of the refrigerant to the evaporator. Therefore, offensive smells are covered with condensate for a long time.
In another aspect, the intermittent operation mode stops when the air passing the evaporator exceeds the wet-bulb temperature of the evaporator. When the temperature of the air flowing through the evaporator has exceeded the wet-bulb temperature of the evaporator, the offensive smells usually have scattered. Therefore, the rate of operation of the compressor is reduced to reduce fuel consumption by stopping the intermittent operation mode when the temperature of the air after passing the evaporator exceeds the wet-bulb temperature.
The temperature of the air passing the evaporator sometimes remains below the wet-bulb temperature depending on the operating condition of the air-conditioning system. As such, in another aspect, when the operation frequency of the compressor has reached a specific frequency after starting the intermittent operation mode, the intermittent operation mode will stop. Prolonged continuous execution of the intermittent operation mode, therefore, can be prevented.
Next, In another aspect, the first predetermined time may be increased according to an increase in the humidity of air introduced into the air-conditioner casing.
In another aspect, the first predetermined time To may be increased according to an increase in air humidity introduced into the air-conditioner casing.
In another aspect, the first predetermined time To may be increased according to a decrease in the volume of air flowing in the air-conditioner casing.
In another aspect, the first predetermined time To in the inside air circulation mode in which the inside air of the vehicle is introduced into the air-conditioner casing may be increased as compared with that in the outside air introduction mode in which the outside air is introduced into the air-conditioner casing.
Furthermore, in another aspect, the first predetermined time To may be decreased according to an increase in vehicle speed, in the outside air introduction mode in which the outside air is introduced into the air-conditioner casing.
In another aspect, the first predetermined time To may be increased according to an increase in the amount of solar radiation entering the vehicle interior in the inside air circulation mode in which the inside air of the vehicle interior is introduced into the air-conditioner casing.
When the compressor is driven by the driving source, it is desirable to stop the intermittent operation mode when stopping the driving source as stated in claim 11 of this invention.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In the drawings: